/*
 * Copyright (c) 2014, alekstheod <email>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *     * Neither the name of the <organization> nor the
 *     names of its contributors may be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY alekstheod <email> ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL alekstheod <email> BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef ERRORFUNCTION_H
#define ERRORFUNCTION_H
#include <Utilities/Math/Math.h>

namespace nn {

namespace bp {
  
template<typename Var>
struct SquaredError {
    template<typename Iterator, typename ProtoIterator>
    Var operator()(Iterator outputBegin, Iterator outputEnd, ProtoIterator protoBegin) {
        //Calculate error
        Var sum = 0;
        while(outputBegin != outputEnd ) {
            Var error = *outputBegin - *protoBegin;
            sum += error*error;
            outputBegin++;
            protoBegin++;
        }

        return sum;
    }
};


template<typename Var>
struct CrossEntropyError {
    template<typename Iterator, typename ProtoIterator>
    Var operator()(Iterator outputBegin, Iterator outputEnd, ProtoIterator protoBegin) {
        //Calculate error
        Var sum = 0;
        while(outputBegin != outputEnd ) {
            Var out = *outputBegin;
            out = utils::log( out );
            sum -= out*(*protoBegin);// - (1.f-*protoBegin)*utils::log(1.-*outputBegin);
            outputBegin++;
            protoBegin++;
        }

        return sum;
    }
};

}

}
#endif // ERRORFUNCTION_H
